In recent years, with the continuous development of communication technologies, the traditional Human to Human (H2H) communication and exchange becomes more convenient, and the Machine to Machine (M2M) connection and dialogue also gradually becomes the mainstream of communication development.
M2M communication refers to the communication between machines. Being different from the traditional H2H communication, M2M can automatically complete collection, processing and transmission of data without manual intervention. One important characteristic of the M2M communication is a relatively large number of user equipments, and the number of the user equipments in Machine Type Communication (MTC) is far larger than that of the user equipments in the H2H communication, which is generally several tens of times of that of the user equipments in the H2H communication.
The M2M mode has been applied to many fields, such as water meter statistics, electric meter statistics, gas meter statistics, hydrological monitoring and the like, where these user equipments belong to a same user, for example, electric meters belong to a same power company, water meters belong to a same tap water company, etc., or these user equipments are relatively densely distributed in a region, such as hydrological monitoring. When the user needs to send common information to a certain user equipment belonging to the user or certain user equipments belonging to the user in the certain region, if each user equipment belonging to the user is paged or the information with same content is sent to each user equipment belonging to the user, the waste of network resources is caused to a certain extent.
In a Long Term Evolution (LTE) system, a data transmission channel is a shared channel, and uplink and downlink data transmission of the user equipments is realized based on scheduling. In the scheduling process, the user equipments need to be addressed. At present, a 16-bit Radio Network Temporary Identifier (RNTI) way is mainly used for addressing the user equipments. The RNTI has a variety of different types for different purposes and the common types comprise: a Paging Radio Network Temporary Identifier (P-RNTI) which is mainly used for addressing when scheduling a paging message; a System Information Radio Network Temporary Identifier (SI-RNTI) which is mainly used for addressing when scheduling a system message; and a Cell Radio Network Temporary Identifier (C-RNTI) which is mainly used for addressing when dynamically scheduling user data.
When the user equipment is in an idle state, the user equipment can receive the paging message and the system message, where the paging message and the system message are broadcast. For the LTE system, the paging message and the system message are transmitted by scheduling, that is, before sending the paging message and the system message, a network side firstly schedules physical resources for transmitting the paging message and the system message, i.e., Physical Downlink Shared Channel (PDSCH) resources, through a Physical Downlink Control Channel (PDCCH). For the paging message, the network side scrambles the PDCCH through the P-RNTI; and for the system message, the network side scrambles the PDCCH through the SI-RNTI. When the user equipment descrambles the PDCCH, the user equipment can respectively use the P-RNTI corresponding to the paging message and the SI-RNTI corresponding to the system message to descramble the PDCCH, thereby correctly obtaining scheduling information carried by the PDCCH. The user equipment receives the paging message or the system message in the indicated physical resource position according to the scheduling information carried on the PDCCH.
In order to reduce power consumption, the user equipment in the idle state monitors the paging message in a Discontinuous Reception (DRX) form according to a certain cycle, namely wakes up periodically to monitor the paging message scheduled by the PDCCH which is scrambled by the P-RNTI in a fixed position. The cycle of monitoring the scheduled paging message is called as a Paging DRX cycle, and the occasion of monitoring the scheduled paging message is called as Paging Occasion (PO). The formula of calculating System Frame Number (SFN) by the user equipment is as follows:SFN mod T=(T div N)*(UE_ID mod N)  (formula I)
Where SFN is the position number of a radio frame where the PO is located, T is the Paging DRX cycle, N is decided by the configurations of the network side, and UE_ID is the International Mobile Subscriber Identity (IMSI) of the user equipment.
The user equipment can calculate the SFN of the occasion when the user equipment monitors the scheduled paging message according to the formula I, but the specific subframe in the radio frame, in which the scheduling of the paging message by the network side is monitored, still needs to be determined by i_s=floor (UE_ID/N) mod Ns (formula II); where i_s is the position number of the subframe in the radio frame where the PO is located, and N and Ns are decided by network configurations.
Similarly, the network side can calculate the position number of the radio frame of the occasion when each user equipment monitors the paging message according to the formula I, and calculate the specific subframe in which each user equipment monitors the scheduling of the paging message by the network side according to the formula II, so that the network side can schedule the paging message of the user equipment in the position where the subframe is located when the network side needs to send the paging message to the user equipment.
As can be known from the formula I and the formula II, if different user equipments use different UE_IDs, the numbers of the specific subframes where the PO is located, which are obtained by calculation, may be different, but if different user equipments use the same UE_ID, the numbers of the specific subframes where the PO is located, which are obtained by calculation, must be the same.
For a Universal Mobile Telecommunications System (UMTS), a high speed data transmission technology, i.e., High Speed Downlink Packet Access (HSDPA)/High Speed Uplink Packet Access (HSUPA), is introduced after an R5 version. The HSDPA is used for downlink data transmission, and the HSUPA is used for uplink data transmission. The HSDPA adopts a scheduling-based data transmission mode to perform downlink data transmission and mainly comprises two physical channels, namely a High Speed Shared Control Channel (HS-SCCH) and a High Speed Physical Downlink Shared Channel (HS-PDSCH), where the HS-SCCH is used for scheduling and carrying physical resources which are allocated by the network side and used for data transmission, namely HS-PDSCH resources, and the HS-PDSCH is specifically used for bearing the data. The HS-SCCH uses a High Speed Downlink Shared Channel Radio Network Temporary Identifier (H-RNTI) for scrambling. The H-RNTI is allocated by a Radio Network Controller (RNC). When a user equipment enters the connection state, the RNC allocates an H-RNTI to the user equipment. In the downlink data transmission process, the user equipment uses the allocated H-RNTI to monitor the HS-SCCH, and if the HS-SCCH is correctly descrambled, the user equipment can receive the data sent from the network side to the user equipment at the physical resources allocated by the network side.
In the UMTS system, the user equipment in the idle state also monitors the paging message in the DRX form, but the transmission mechanism of the paging message of the UMTS system is different from the transmission mechanism of the paging message of the LTE system. In the UMTS system, the user equipment needs to receive a Paging Indicator Channel (PICH) in the DRX form. The PICH does not carry the specific content of the paging message and can only indicate whether the user equipment is paged. The content of the PICH consists of a series (NPI) of paging indicators Pq, q=0, . . . , NPI−1, Pq ε {0,1}, and the length LPI of each paging indicator in the PICH block can be 2, 4 or 8 data symbols. Under the modulation of Quadrature Phase Shift Keying (QPSK), LPI corresponds to 4, 8 or 16 consecutive bits. In the burst of the PICH, NPIB=352 bits are used for carrying the paging indication. The number NPI of the paging indicators can be calculated by NPI=NPIB/(2 LPI) (formula III). One PICH block can consist of NPICH consecutive paging indication frames, where the NPICH is configured by a high layer. Therefore, the number of the paging indicators in one PICH block is NP=NPICH*NPI. Based on the above description, the calculation formula of the paging indicator of the user equipment is as follows:PI=(IMSI div 8192)mod NP  (Formula IV)
The value of the PI is associated with the paging indication Pq of the nth frame of one PICH block, and q and n are obtained according to the following formula: q=PI mod NPI and n=PI div NPI.
As can be known from the formula IV, the user equipment reads the paging indicator PI in the corresponding position, and if the bits of the PI are all 1 {1, 1, 1 . . . , 1}, it means that the user equipment is required to receive the PICH channel and then page a paging subchannel in the block so as to determine whether paging of the user equipment is contained in the paging message; otherwise, the subsequent paging message does not need to be received.
If the user equipment finds that it is paged, the user equipment receives the paging message on the selected physical resource, namely a Secondary Common Control Physical Channel (SCCPCH), at a fixed time interval (Ngap, the value is configured by the network side). The network side can configure multiple SCCPCH channels, the method of selecting the SCCPCH channel for receiving the paging message by the user equipment is determined according to S-CCPCH index=IMSI mod K (formula V), where the S-CCPCH index is a number identifying the SCCPCH channel.
As can be known from the above discussion, in the UMTS system, when the user equipment in the idle state monitors its own paging message, the user equipment also needs to select the resource which needs to be used by itself from common resources according to its own IMSI. If the user equipments in one group use the same identity, the user equipments can monitor the same information at the same occasion.
In the prior art, the modes of transmitting data to a group consisting of at least one user equipment comprise system message broadcasting and paging message. As for the data transmission mode of the system message broadcasting, the system message is suitable for transmitting the data information to all the user equipments belonging to the same user and not suitable for transmitting the data information to a certain group of user equipments; and as for the data transmission mode of the paging message, the carried resources are limited, and when more data is carried in the data transmission mode, normal user equipments can be affected, and particularly, the receiving of the normal paging message by the normal edge user equipments can be affected. As can be known from the above analysis, when downlink data is transmitted to a certain group of user equipments through the prior art, the problem of low utilization rate of the network resources exists. Thus, there is no group-based downlink data transmission mode which is suitable for transmitting data to a certain group of user equipments at present.